1. Field of the Invention
The present invention relates generally to a computer architecture and method of service preemption for mobile terminals in a mobile satellite communication system, and more particularly, to a computer architecture and method of performing continuous reception (full-duplex receiver function) during message channel transmission.
2. Background of the Related Art
FIG. 1 illustrates the general layout of a mobile communication system. A vehicle 18, usually transporting cargo, moves along a transport route. The route can be one that is well known, or it can be one that is being newly travelled by the vehicle. The vehicle is preferably equipped with at least one mobile sensing station, which functions to detect predetermined events or conditions (such as collisions or impacts, potholes or uneven tracks or the like) along the travel route, and transmit data regarding those conditions using the mobile communicator system (not shown) via orbiting satellite 14 to a remote satellite ground station 8 via satellite antenna 10. The satellite ground station 8 transfers the data received from the mobile communicator system to a dispatch or fleet management center to analyze and evaluate the data.
Part of the data transmitted from the mobile sensing station is positional data received or detected from satellite 14 or a separate satellite which is part of a satellite navigation system. Examples of presently available systems are LORAN or the current Global Position System (GPS).
Navigational data sent to the mobile sensing station preferably utilizes a Standard-C data protocol format, which is commonly used in the maritime industry. Experience has indicated that this is the most reliable method of sending navigational data from one mobile station to another. However, other navigation or location systems can be used. For example, a series of radio repeaters located along a predetermined route can track the location of a specific vehicle and can be used to send location data to the mobile communicator as is done by satellite 14 in FIG. 1. Also, other data transfer formats can be used, depending on the navigational system, the transport route, the vehicle and the communication system for transmitting data from the mobile communicator system.
While FIG. 1 illustrates communication between the mobile communicator system in vehicle 18 to satellite 14, the mobile communicator system may also communicate with the fleet management center by means of a cellular telephone system. In this variation, a cellular transceiver is used capable of automatically accessing cellular ground station 4 as it passes from one cell into another. While such equipment may be more complex and expensive than the satellite uplink embodied in FIG. 1, it facilitates easy communication of instructions from the central controller to the mobile sensing station.
The fleet dispatch center includes a central controller that stores the data sent from the mobile communicator system and arranges it so that it can be used in a display, for example, by vehicle 18. The central controller is expected to handle data from a variety of routes, each travelled by a plurality of vehicles optionally having mobile sensing stations. Since the data are preferably transmitted from the mobile communicator system in ASCII format, the user terminal can access selected data from the central controller using a personal computer (PC), a modem and standard communication software.
With the appropriate software, a display of the desired transport route can be generated at the PC terminal, and information is received from various vehicles having mobile communicator systems travelling along that route. For example, boat 16 in FIG. 1 also includes a mobile communicator system for communication with satellite 14. In addition, even vehicles or subscribers who do not contain the mobile communicator system can communicate with the mobile communicator system. For example, vehicle 20 may communicate with satellite 14 via cellular antenna 6, cellular switching office 4, satellite ground station 8 and satellite antenna 10. Similarly, plain old telephone service (POTS) telephone 12 may also communicate with satellite 14 via switching office 8, satellite ground station 8 and satellite antenna 10. Thus, the mobile communicator system may be used to exchange data from among various different vehicles.
The Federal Communications Commission (FCC) has generally required communication system providers to provide some capability for securely and reliably transmitting a priority message in the presence of a priority event. Since various different users utilize the communication system, and the communication system provides the capability of supporting a wide audience, it is desirable to provide a priority and/or preemption capability that can transmit a priority and/or preemption message to various mobile communication systems.
I have determined that the priority and/or preemption capability preferably includes the ability to warn mobile communication systems of a preemption event that may be imminent. I have also determined that the priority and preemption capability must be implemented in an efficient and expedient manner to ensure that communication resources are freed in a timely manner to transmit a priority message. I have also determined that the priority and/or preemption capability optionally includes alteration of functionality in the mobile communication system to facilitate same.